I hate it when manufacturers mess around with critical components dimensions, when the change / upgrade bits. I encountered a doozy yesterday. I bought some 25mm Tannus tyres to replace the 28mm ones, I fitted to one of my bikes last year. I removed the old ones, using the Allen key and fitting tool technique. Job’s a good’un so far. Then I fitted the new ones onto the rim. This took a bit more swearing, but they are designed to be tight for a good reason, but job’s a good’un again. Then I went to push the fixing pins into the clincher hooks. Bugger, they won’t go, no matter how much swearing and ‘hitting with a hammer’ was employed. So, I checked the sizing of the new tyres, against the old ones. Old ones: 622x28mm. New ones 622x25mm. Okay, all good. A bit more swearing and hammer hitting failed to get the new pins located. So I checked the size of the strip on the tyres that sits in the rim and is peculiar / critical to / with these tyres. ( inner rim width ). Wheels: 16mm. Old 28mm tyres : 15mm. New 25mm tyres : 16mm. That explains it then . To be fair, the fitting chart on the Tannus website does mention it, and the updated 2017 Mavic Aksiums do have a 17mm inner rim width, but the ones I was using, are 16mm width. So I shall transfer the new 25mm tyres to the bike with the 2017 Mavic Aksiums on it. I’d better get my hammer back out.